A stator commonly includes a winding core and a plurality of winding coils, and the winding core can define a plurality of winding grooves configured to receive the winding coils. The traditional winding methods are a lap winding method and a wave-shape winding method. The lap winding method can reduce the power density of a motor due to increasing a length of an end of each of the winding coils. The wave-shape winding method can reduce an output torque of a motor.